Graphene oxide-based battery-type cathodes for hybrid supercapacitors: enhancing energy density through structural and material design

Hybrid supercapacitors (HSCs) are a recent evolution in energy storage systems that integrate the high power of capacitors with the high energy density of batteries. This review focuses on graphene oxide (GO)-based battery-type cathodes, which are crucial in extending the voltage window and enhancing the overall energy density of HSCs. GO offers high conductivity, structural tunability, and surface functionality, making it a versatile framework for constructing composite cathodes. Summarizing recent advances in GO-based hybrid electrodes, including metal oxides/sulfides, molecular clusters, and ternary systems, with emphasis on their structural design, electrochemical performance, and synergistic charge storage mechanisms. Theoretical models such as i=Cv^b and E= 1/2 CV² are also discussed to interpret rate behavior and energy storage. Finally, future perspectives highlight nanostructure engineering and multi-phase integration as promising strategies to improve GO-based cathode performance in HSCs further.